by Keyword: Imaging
Blanco-Fernandez, G, Blanco-Fernandez, B, Fernandez-Ferreiro, A, Otero-Espinar, FJ, (2023). Lipidic lyotropic liquid crystals: Insights on biomedical applications Advances In Colloid And Interface Science 313, 102867
Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engi-neering and molecular imaging) and route of administration is examined. Further discussion of the main limi-tations and perspectives of lipidic LLCs in biomedical applications are also provided.Statement of significance: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.
JTD Keywords: Cancer, Drug delivery, Drug-delivery-systems, Glycerol monooleate, Imaging, In-situ, Liquid crystals, Nano-carriers, Nanoparticles, Phase-behavior, Stratum-corneum, Sustained-release, Tissue engineering, Vegetable-oil, Water
De Lama-Odría, María del Carmen, Valle, Luis Jdel, Puiggalí, Jordi, (2023). Lanthanides-Substituted Hydroxyapatite for Biomedical Applications International Journal Of Molecular Sciences 24, 3446
Lately, there has been an increasing demand for materials that could improve tissue regenerative therapies and provide antimicrobial effects. Similarly, there is a growing need to develop or modify biomaterials for the diagnosis and treatment of different pathologies. In this scenario, hydroxyapatite (HAp) appears as a bioceramic with extended functionalities. Nevertheless, there are certain disadvantages related to the mechanical properties and lack of antimicrobial capacity. To circumvent them, the doping of HAp with a variety of cationic ions is emerging as a good alterative due to the different biological roles of each ion. Among many elements, lanthanides are understudied despite their great potential in the biomedical field. For this reason, the present review focuses on the biological benefits of lanthanides and how their incorporation into HAp can alter its morphology and physical properties. A comprehensive section of the applications of lanthanides-substituted HAp nanoparticles (HAp NPs) is presented to unveil the potential biomedical uses of these systems. Finally, the need to study the tolerable and non-toxic percentages of substitution with these elements is highlighted.
JTD Keywords: biolabeling, biomedicine, biosensors, bone regeneration, calcium, cancer treatment, cationic ions, cell imaging, cerium, doped hap, implants, in-vitro bioactivity, lanthanidessubstitutions, nanoparticles, radiation synovectomy, sm-153 particulate hydroxyapatite, structural-characterization, theragnostics, theranostic nanoplatforms, Europium-doped hydroxyapatite, Hydroxyapatite
Blanco-Fernandez G, Blanco-Fernandez B, Fernández-Ferreiro A, Otero-Espinar F, (2023). Bringing lipidic lyotropic liquid crystal technology into biomedicine Trends In Pharmacological Sciences 44, 7-10
Campo-Perez, V, Guallar-Garrido, S, Luquin, M, Sanchez-Chardi, A, Julian, E, (2022). The High Plasticity of Nonpathogenic Mycobacterium brumae Induces Rapid Changes in Its Lipid Profile during Pellicle Maturation: The Potential of This Bacterium as a Versatile Cell Factory for Lipid Compounds of Therapeutic Interest International Journal Of Molecular Sciences 23, 13609
The immunomodulatory potential of mycobacteria to be used for therapeutic purposes varies by species and culture conditions and is closely related to mycobacterial lipid composition. Although the lipids present in the mycobacterial cell wall are relevant, lipids are mainly stored in intracellular lipid inclusions (ILIs), which have emerged as a crucial structure in understanding mycobacteria-host interaction. Little is known about ILI ultrastructure, production, and composition in nonpathogenic species. In this study, we compared the lipid profiles of the nonpathogenic immunomodulatory agent Mycobacterium brumae during pellicle maturation under different culture conditions with qualitative and quantitative approaches by using high-resolution imaging and biochemical and composition analyses to understand ILI dynamics. The results showed wax esters, mainly in early stages of development, and acylglycerols in mature ILI composition, revealing changes in dynamics, amount, and morphometry, depending on pellicle maturation and the culture media used. Low-glycerol cultures induced ILIs with lower molecular weights which were smaller in size in comparison with the ILIs produced in glycerol-enriched media. The data also indicate the simple metabolic plasticity of lipid synthesis in M. brumae, as well as its high versatility in generating different lipid profiles. These findings provide an interesting way to enhance the production of key lipid structures via the simple modulation of cell culture conditions.
JTD Keywords: Bodies, Cell wall, Electron microscopy, Growth, In-vitro, Intrabacterial, Lipid inclusions, Mycobacterium, Prokaryotes, Triacylglycerol, Tuberculosis, Ultrastructural imaging, Virulence, Wax esters
Martens KJA, Gobes M, Archontakis E, Brillas RR, Zijlstra N, Albertazzi L, Hohlbein J, (2022). Enabling Spectrally Resolved Single-Molecule Localization Microscopy at High Emitter Densities Nano Letters 22, 8618-8625
Single-molecule localization microscopy (SMLM) is a powerful super-resolution technique for elucidating structure and dynamics in the life- and material sciences. Simultaneously acquiring spectral information (spectrally resolved SMLM, sSMLM) has been hampered by several challenges: an increased complexity of the optical detection pathway, lower accessible emitter densities, and compromised spatio-spectral resolution. Here we present a single-component, low-cost implementation of sSMLM that addresses these challenges. Using a low-dispersion transmission grating positioned close to the image plane, the +1stdiffraction order is minimally elongated and is analyzed using existing single-molecule localization algorithms. The distance between the 0th and 1st order provides accurate information on the spectral properties of individual emitters. This method enables a 5-fold higher emitter density while discriminating between fluorophores whose peak emissions are less than 15 nm apart. Our approach can find widespread use in single-molecule applications that rely on distinguishing spectrally different fluorophores under low photon conditions.
JTD Keywords: cells, multicolor imaging, nanoscopy, particle tracking, point accumulation for imaging in nanoscale topography (paint), precision, single-molecule fo?rster resonance energy transfer (smfret), stochastic optical reconstruction microscopy (storm), Diffraction-limit, Multicolor imaging, Point accumulation for imaging in nanoscale topography (paint), Single-molecule förster resonance energy transfer (smfret), Single-molecule spectroscopy, Stochastic optical reconstruction microscopy (storm)
De Lama-Odría, María del Carmen, del Valle, Luis J., Puiggalí, Jordi, (2022). Hydroxyapatite Biobased Materials for Treatment and Diagnosis of Cancer International Journal Of Molecular Sciences 23, 11352
Great advances in cancer treatment have been undertaken in the last years as a consequence of the development of new antitumoral drugs able to target cancer cells with decreasing side effects and a better understanding of the behavior of neoplastic cells during invasion and metastasis. Specifically, drug delivery systems (DDS) based on the use of hydroxyapatite nanoparticles (HAp NPs) are gaining attention and merit a comprehensive review focused on their potential applications. These are derived from the intrinsic properties of HAp (e.g., biocompatibility and biodegradability), together with the easy functionalization and easy control of porosity, crystallinity and morphology of HAp NPs. The capacity to tailor the properties of DLS based on HAp NPs has well-recognized advantages for the control of both drug loading and release. Furthermore, the functionalization of NPs allows a targeted uptake in tumoral cells while their rapid elimination by the reticuloendothelial system (RES) can be avoided. Advances in HAp NPs involve not only their use as drug nanocarriers but also their employment as nanosystems for magnetic hyperthermia therapy, gene delivery systems, adjuvants for cancer immunotherapy and nanoparticles for cell imaging.
JTD Keywords: antitumoral, cell imaging, controlled-release, drug-carrier, efficient drug-delivery, fatty-acid-metabolism, fe3o4 nanoparticles, gene delivery, hydroxyapatite, hyperthermia, immunotherapy, in-vitro, magnetic hydroxyapatite, nano-hydroxyapatite, protein adsorption, tumor-growth, Calcium-phosphate nanoparticles, Cancer
Moussa, Dina G., Sharma, Ashok K., Mansour, Tamer A, Witthuhn, Bruce, Perdigão, Jorge, Rudney, Joel D., Aparicio, Conrado, Gomez, Andres, (2022). Functional signatures of ex-vivo dental caries onset Journal Of Oral Microbiology 14, 2123624
JTD Keywords: bacteria, biofilms, children, generation, genomics, longitudinal model, metabolism, metabolomics, microscopy, non-invasive bioimaging, oral microbiome, plaque, restorations, signatures, Dental caries, Field-emission sem
Murar M, Albertazzi L, Pujals S, (2022). Advanced Optical Imaging-Guided Nanotheranostics toward Personalized Cancer Drug Delivery Nanomaterials 12, 399
Nanomedicine involves the use of nanotechnology for clinical applications and holds promise to improve treatments. Recent developments offer new hope for cancer detection, prevention and treatment; however, being a heterogenous disorder, cancer calls for a more targeted treatment approach. Personalized Medicine (PM) aims to revolutionize cancer therapy by matching the most effective treatment to individual patients. Nanotheranostics comprise a combination of therapy and diagnostic imaging incorporated in a nanosystem and are developed to fulfill the promise of PM by helping in the selection of treatments, the objective monitoring of response and the planning of follow-up therapy. Although well-established imaging techniques, such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT), are primarily used in the development of theranostics, Optical Imaging (OI) offers some advantages, such as high sensitivity, spatial and temporal resolution and less invasiveness. Additionally, it allows for multiplexing, using multi-color imaging and DNA barcoding, which further aids in the development of personalized treatments. Recent advances have also given rise to techniques permitting better penetration, opening new doors for OI-guided nanotheranostics. In this review, we describe in detail these recent advances that may be used to design and develop efficient and specific nanotheranostics for personalized cancer drug delivery. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
JTD Keywords: 5-aminolevulinic acid, cancer, contrast agents, in-vivo, malignant gliomas, multifunctional nanoparticles, nanomedicine, optical imaging, ovarian-cancer, personalized medicine, quantum dots, silica nanoparticles, targeted probes, theranostics, Cancer, Nanomedicine, Optical imaging, Personalized medicine, Superparamagnetic iron-oxide, Theranostics
Páscoa dos Santos F, Verschure PFMJ, (2022). Excitatory-Inhibitory Homeostasis and Diaschisis: Tying the Local and Global Scales in the Post-stroke Cortex Frontiers In Systems Neuroscience 15, 806544
Maintaining a balance between excitatory and inhibitory activity is an essential feature of neural networks of the neocortex. In the face of perturbations in the levels of excitation to cortical neurons, synapses adjust to maintain excitatory-inhibitory (EI) balance. In this review, we summarize research on this EI homeostasis in the neocortex, using stroke as our case study, and in particular the loss of excitation to distant cortical regions after focal lesions. Widespread changes following a localized lesion, a phenomenon known as diaschisis, are not only related to excitability, but also observed with respect to functional connectivity. Here, we highlight the main findings regarding the evolution of excitability and functional cortical networks during the process of post-stroke recovery, and how both are related to functional recovery. We show that cortical reorganization at a global scale can be explained from the perspective of EI homeostasis. Indeed, recovery of functional networks is paralleled by increases in excitability across the cortex. These adaptive changes likely result from plasticity mechanisms such as synaptic scaling and are linked to EI homeostasis, providing a possible target for future therapeutic strategies in the process of rehabilitation. In addition, we address the difficulty of simultaneously studying these multiscale processes by presenting recent advances in large-scale modeling of the human cortex in the contexts of stroke and EI homeostasis, suggesting computational modeling as a powerful tool to tie the meso- and macro-scale processes of recovery in stroke patients. Copyright © 2022 Páscoa dos Santos and Verschure.
JTD Keywords: balanced excitation, canonical microcircuit, cerebral-cortex, cortical excitability, cortical reorganization, diaschisis, excitability, excitatory-inhibitory balance, functional networks, homeostatic plasticity, ischemic-stroke, neuronal avalanches, photothrombotic lesions, state functional connectivity, whole-brain models, Algorithm, Biological marker, Brain, Brain cell, Brain cortex, Brain function, Brain radiography, Cerebrovascular accident, Cortical reorganization, Diaschisis, Down regulation, Excitability, Excitatory-inhibitory balance, Fluorine magnetic resonance imaging, Functional networks, Homeostasis, Homeostatic plasticity, Human, Motor dysfunction, Neuromodulation, Plasticity, Pyramidal nerve cell, Review, Simulation, Stroke, Stroke patient, Theta-burst stimulation, Visual cortex
Chausse, Victor, Schieber, Romain, Raymond, Yago, Ségry, Brian, Sabaté, Ramon, Kolandaivelu, Kumaran, Ginebra, Maria-Pau, Pegueroles, Marta, (2021). Solvent-cast direct-writing as a fabrication strategy for radiopaque stents Additive Manufacturing 48,
JTD Keywords: biocompatibility, bioresorbable stents, degradation, mechanical-properties, poly(epsilon-caprolactone), poly-l-lactic acid, polylactide, radiopacity, thermogel, x-ray imaging, Barium sulfate, Biocompatibility, Bioresorbable, Bioresorbable scaffolds, Bioresorbable stent, Bioresorbable stents, Blood vessels, Computerized tomography, Controlled drug delivery, Coronary heart disease, Direct-writing, Endothelial cells, Fabrication strategies, Injection molding, Lactic acid, Poly-l-lactic acid, Poly-l-lactic acids, Radiopacity, Scaffolds (biology), Solvent cast, Solvent-cast direct-writing, Solvents, Stents, Struts, Sulfur compounds, Targeted drug delivery, X-ray imaging
Riera, Roger, Hogervorst, Tim P., Doelman, Ward, Ni, Yan, Pujals, Silvia, Bolli, Evangelia, Codée, Jeroen DC., van Kasteren, Sander I., Albertazzi, Lorenzo, (2021). Single-molecule imaging of glycan–lectin interactions on cells with Glyco-PAINT Nature Chemical Biology 17, 1281-1288
Most lectins bind carbohydrate ligands with relatively low affinity, making the identification of optimal ligands challenging. Here we introduce a point accumulation in nanoscale topography (PAINT) super-resolution microscopy method to capture weak glycan-lectin interactions at the single-molecule level in living cells (Glyco-PAINT). Glyco-PAINT exploits weak and reversible sugar binding to directly achieve single-molecule detection and quantification in cells and is used to establish the relative kon and koff rates of a synthesized library of carbohydrate-based probes, as well as the diffusion coefficient of the receptor-sugar complex. Uptake of ligands correlates with their binding affinity and residence time to establish structure-function relations for various synthetic glycans. We reveal how sugar multivalency and presentation geometry can be optimized for binding and internalization. Overall, Glyco-PAINT represents a powerful approach to study weak glycan-lectin interactions on the surface of living cells, one that can be potentially extended to a variety of lectin-sugar interactions.© 2021. The Author(s), under exclusive licence to Springer Nature America, Inc.
JTD Keywords: dc-sign, density, dimerization, endocytosis, lateral mobility, ligand-binding, mannose receptor, proteins, recognition, Animal, Animals, Cell membrane, Cell membrane permeability, Chemistry, Cho cell line, Cho cells, Cricetulus, Cysteine-rich domain, Kinetics, Lectin, Lectins, Ligand, Ligands, Molecular library, Multivariate analysis, Polysaccharide, Polysaccharides, Procedures, Protein binding, Single molecule imaging, Small molecule libraries, Structure activity relation, Structure-activity relationship
Wang Y, Friedrich H, Voets IK, Zijlstra P, Albertazzi L, (2021). Correlative imaging for polymer science Journal Of Polymer Science 59, 1232-1240
The characterization of polymeric materials is key towards the understanding of structure–activity relations and therefore for the rational design of novel and improved materials for a myriad of applications. Many microscopy techniques are currently used, with electron microscopy, fluorescence microscopy, and atomic force microscopy being the most relevant. In this perspective paper, we discuss the use of correlative imaging, that is, the combination of multiple imaging methodologies on the same sample, in the field of polymeric materials. This innovative approach is emerging as a powerful tool to unveil the structure and functional properties of biological and synthetic structures. Here we discuss the possibilities of correlative imaging and highlight their potential to answer open questions in polymer science.
JTD Keywords: correlative imaging, electron microscopy, material characterization, resolution microscopy, super‐, Atomic force microscopy, Correlative imaging, Electron microscopy, Material characterization, Super-resolution microscopy
Arista-Romero M, Pujals S, Albertazzi L, (2021). Towards a Quantitative Single Particle Characterization by Super Resolution Microscopy: From Virus Structures to Antivirals Design Frontiers In Bioengineering And Biotechnology 9,
In the last year the COVID19 pandemic clearly illustrated the potential threat that viruses pose to our society. The characterization of viral structures and the identification of key proteins involved in each step of the cycle of infection are crucial to develop treatments. However, the small size of viruses, invisible under conventional fluorescence microscopy, make it difficult to study the organization of protein clusters within the viral particle. The applications of super-resolution microscopy have skyrocketed in the last years, converting this group into one of the leading techniques to characterize viruses and study the viral infection in cells, breaking the diffraction limit by achieving resolutions up to 10 nm using conventional probes such as fluorescent dyes and proteins. There are several super-resolution methods available and the selection of the right one it is crucial to study in detail all the steps involved in the viral infection, quantifying and creating models of infection for relevant viruses such as HIV-1, Influenza, herpesvirus or SARS-CoV-1. Here we review the use of super-resolution microscopy (SRM) to study all steps involved in the viral infection and antiviral design. In light of the threat of new viruses, these studies could inspire future assays to unveil the viral mechanism of emerging viruses and further develop successful antivirals against them.
JTD Keywords: antivirals, characterization, imaging, super-resolution, virus, Antivirals, Characterization, Imaging, Super-resolution, Virus
Delcanale, P., Porciani, D., Pujals, S., Jurkevich, A., Chetrusca, A., Tawiah, K. D., Burke, D. H., Albertazzi, L., (2020). Aptamers with tunable affinity enable single-molecule tracking and localization of membrane receptors on living cancer cells Angewandte Chemie - International Edition 59, (42), 18546-18555
Tumor cell-surface markers are usually overexpressed or mutated protein receptors for which spatiotemporal regulation differs between and within cancers. Single-molecule fluorescence imaging can profile individual markers in different cellular contexts with molecular precision. However, standard single-molecule imaging methods based on overexpressed genetically encoded tags or cumbersome probes can significantly alter the native state of receptors. We introduce a live-cell points accumulation for imaging in nanoscale topography (PAINT) method that exploits aptamers as minimally invasive affinity probes. Localization and tracking of individual receptors are based on stochastic and transient binding between aptamers and their targets. We demonstrated single-molecule imaging of a model tumor marker (EGFR) on a panel of living cancer cells. Affinity to EGFR was finely tuned by rational engineering of aptamer sequences to define receptor motion and/or native receptor density.
JTD Keywords: Aptamers, Cell-surface receptors, Live-cell imaging, PAINT, Single-molecule tracking
Mas, S., Torro, A., Fernández, L., Bec, N., Gongora, C., Larroque, C., Martineau, P., de Juan, A., Marco, S., (2020). MALDI imaging mass spectrometry and chemometric tools to discriminate highly similar colorectal cancer tissues Talanta 208, 120455
Intratumour heterogeneity due to cancer cell clonal evolution and microenvironment composition and tumor differences due to genetic variations between patients suffering of the same cancer pathology play a crucial role in patient response to therapies. This study is oriented to show that matrix-assisted laser-desorption ionization-Mass spectrometry imaging (MALDI-MSI), combined with an advanced multivariate data processing pipeline can be used to discriminate subtle variations between highly similar colorectal tumors. To this aim, experimental tumors reproducing the emergence of drug-resistant clones were generated in athymic mice using subcutaneous injection of different mixes of two isogenic cell lines, the irinotecan-resistant HCT116-SN50 (R) and its sibling human colon adenocarcinoma sensitive cell line HCT116 (S). Because irinotecan-resistant and irinotecan-sensitive are derived from the same original parental HCT116 cell line, their genetic characteristics and molecular compositions are closely related. The multivariate data processing pipeline proposed relies on three steps: (a) multiset multivariate curve resolution (MCR) to separate biological contributions from background; (b) multiset K-means segmentation using MCR scores of the biological contributions to separate between tumor and necrotic parts of the tissues; and (c) partial-least squares discriminant analysis (PLS-DA) applied to tumor pixel spectra to discriminate between R and S tumor populations. High levels of correct classification rates (0.85), sensitivity (0.92) and specificity (0.77) for the PLS-DA classification model were obtained. If previously labelled tissue is available, the multistep modeling strategy proposed constitutes a good approach for the identification and characterization of highly similar phenotypic tumor subpopulations that could be potentially applicable to any kind of cancer tissue that exhibits substantial heterogeneity. Â© 2019 Elsevier B.V.
JTD Keywords: Chemometrics, Colorectal cancer, MALDI imaging, Multivariate analysis, Tumor heterogeneity
Pujals, S., Feiner-Gracia, N., Delcanale, P., Voets, I., Albertazzi, L., (2019). Super-resolution microscopy as a powerful tool to study complex synthetic materials Nature Reviews Chemistry 3, (2), 68-84
Understanding the relations between the formation, structure, dynamics and functionality of complex synthetic materials is one of the great challenges in chemistry and nanotechnology and represents the foundation for the rational design of novel materials for a variety of applications. Initially conceived to study biology below the diffraction limit, super-resolution microscopy (SRM) is emerging as a powerful tool for studying synthetic materials owing to its nanometric resolution, multicolour ability and minimal invasiveness. In this Review, we provide an overview of the pioneering studies that use SRM to visualize materials, highlighting exciting recent developments such as experiments in operando, wherein materials, such as biomaterials in a biological environment, are imaged in action. Moreover, the potential and the challenges of the different SRM methods for application in nanotechnology and (bio)materials science are discussed, aiming to guide researchers to select the best SRM approach for their specific purpose.
JTD Keywords: Bioinspired materials, Imaging techniques
Pollastri, S., Jorba, I., Hawkins, T. J., Llusià , J., Michelozzi, M., Navajas, D., Peñuelas, J., Hussey, P. J., Knight, M. R., Loreto, F., (2019). Leaves of isoprene-emitting tobacco plants maintain PSII stability at high temperatures New Phytologist 223, (3), 1307-1318
At high temperatures, isoprene-emitting plants display a higher photosynthetic rate and a lower nonphotochemical quenching (NPQ) compared with nonemitting plants. The mechanism of this phenomenon, which may be very important under current climate warming, is still elusive. NPQ was dissected into its components, and chlorophyll fluorescence lifetime imaging microscopy (FLIM) was used to analyse the dynamics of excited chlorophyll relaxation in isoprene-emitting and nonemitting plants. Thylakoid membrane stiffness was also measured using atomic force microscope (AFM) to identify a possible mode of action of isoprene in improving photochemical efficiency and photosynthetic stability. We show that, when compared with nonemitters, isoprene-emitting tobacco plants exposed at high temperatures display a reduced increase of the NPQ energy-dependent component (qE) and stable (1) chlorophyll fluorescence lifetime; (2) amplitude of the fluorescence decay components; and (3) thylakoid membrane stiffness. Our study shows for the first time that isoprene maintains PSII stability at high temperatures by preventing the modifications of the surrounding environment, namely providing a more steady and homogeneous distribution of the light-absorbing centres and a stable thylakoid membrane stiffness. Isoprene photoprotects leaves with a mechanism alternative to NPQ, enabling plants to maintain a high photosynthetic rate at rising temperatures.
JTD Keywords: (High) temperature, Atomic force microscopy (AFM), Chlorophyll fluorescence (quenching and lifetime), Fluorescence lifetime imaging microscopy (FLIM), Isoprene, Nonphotochemical quenching (NPQ), Photosynthesis
Malandrino, Andrea, Trepat, Xavier, Kamm, Roger D., Mak, Michael, (2019). Dynamic filopodial forces induce accumulation, damage, and plastic remodeling of 3D extracellular matrices PLoS Computational Biology 15, (4), e1006684
The mechanical properties of the extracellular matrix (ECM)–a complex, 3D, fibrillar scaffold of cells in physiological environments–modulate cell behavior and can drive tissue morphogenesis, regeneration, and disease progression. For simplicity, it is often convenient to assume these properties to be time-invariant. In living systems, however, cells dynamically remodel the ECM and create time-dependent local microenvironments. Here, we show how cell-generated contractile forces produce substantial irreversible changes to the density and architecture of physiologically relevant ECMs–collagen I and fibrin–in a matter of minutes. We measure the 3D deformation profiles of the ECM surrounding cancer and endothelial cells during stages when force generation is active or inactive. We further correlate these ECM measurements to both discrete fiber simulations that incorporate fiber crosslink unbinding kinetics and continuum-scale simulations that account for viscoplastic and damage features. Our findings further confirm that plasticity, as a mechanical law to capture remodeling in these networks, is fundamentally tied to material damage via force-driven unbinding of fiber crosslinks. These results characterize in a multiscale manner the dynamic nature of the mechanical environment of physiologically mimicking cell-in-gel systems.
JTD Keywords: Collagens, Fibrin, Extracellular matrix, Cross-linking, Cell physiology, Deformation, Fluorescence imaging, Cell biology
Faron, A., Pieper, C. C., Schmeel, F. C., Sprinkart, A. M., Kuetting, D. L. R., Fimmers, R., Trebicka, J., Schild, H. H., Meyer, C., Thomas, D., Luetkens, J. A., (2019). Fat-free muscle area measured by magnetic resonance imaging predicts overall survival of patients undergoing radioembolization of colorectal cancer liver metastases European Radiology 29, (9), 4709-4717
Objectives: To investigate the clinical potential of fat-free muscle area (FFMA) to predict outcome in patients with liver-predominant metastatic colorectal cancer (mCRC) undergoing radioembolization (RE) with 90Yttrium microspheres.
Methods: Patients with mCRC who underwent RE in our center were included in this retrospective study. All patients received liver magnetic resonance imaging including standard T2-weighted images. The total erector spinae muscle area and the intramuscular adipose tissue area were measured at the level of the origin of the superior mesenteric artery and subtracted to calculate FFMA. Cutoff values for definition of low FFMA were 3644 mm2 in men and 2825 mm2 in women. The main outcome was overall survival (OS). For survival analysis, the Kaplan-Meier method and Cox regressions comparing various clinic-oncological parameters which potentially may affect OS were performed.
Results: Seventy-seven patients (28 female, mean age 60 ± 11 years) were analyzed. Mean time between MRI and the following RE was 17 ± 31 days. Median OS after RE was 178 days. Patients with low FFMA had significantly shortened OS compared to patients with high FFMA (median OS: 128 vs. 273 days, p = 0.017). On multivariate Cox regression analysis, OS was best predicted by FFMA (hazard ratio (HR) 2.652; p < 0.001). Baseline bilirubin (HR 1.875; p = 0.030), pattern of tumor manifestation (HR 1.679; p = 0.001), and model of endstage liver disease (MELD) score (HR 1.164; p < 0.001) were also significantly associated with OS.
Conclusions: FFMA was associated with OS in patients receiving RE for treatment of mCRC and might be a new prognostic biomarker for survival prognosis.
JTD Keywords: Brachytherapy, Colorectal cancer, Magnetic resonance imaging, Sarcopenia
Lozano, H., Millán-Solsona, R., Fabregas, R., Gomila, G., (2019). Sizing single nanoscale objects from polarization forces Scientific Reports 9, (1), 14142
Sizing natural or engineered single nanoscale objects is fundamental in many areas of science and technology. To achieve it several advanced microscopic techniques have been developed, mostly based on electron and scanning probe microscopies. Still for soft and poorly adhered samples the existing techniques face important challenges. Here, we propose an alternative method to size single nanoscale objects based on the measurement of its electric polarization. The method is based on Electrostatic Force Microscopy measurements combined with a specifically designed multiparameter quantification algorithm, which gives the physical dimensions (height and width) of the nanoscale object. The proposed method is validated with ~50 nm diameter silver nanowires, and successfully applied to ~10 nm diameter bacterial polar flagella, an example of soft and poorly adhered nanoscale object. We show that an accuracy comparable to AFM topographic imaging can be achieved. The main advantage of the proposed method is that, being based on the measurement of long-range polarization forces, it can be applied without contacting the sample, what is key when considering poorly adhered and soft nanoscale objects. Potential applications of the proposed method to a wide range of nanoscale objects relevant in Material, Life Sciences and Nanomedicine is envisaged.
JTD Keywords: Characterization and analytical techniques, Imaging techniques
Cozzolino, M., Delcanale, P., Montali, C., Tognolini, M., Giorgio, C., Corrado, M., Cavanna, L., Bianchini, P., Diaspro, A., Abbruzzetti, S., Viappiani, C., (2019). Enhanced photosensitizing properties of protein bound curcumin Life Sciences 233, 116710
Aims: The naturally occurring compound curcumin has been proposed for a number of pharmacological applications. In spite of the promising chemotherapeutic properties of the molecule, the use of curcumin has been largely limited by its chemical instability in water. In this work, we propose the use of water soluble proteins to overcome this issue in perspective applications to photodynamic therapy of tumors. Materials and methods: Curcumin was bound to bovine serum albumin and its photophysical properties was studied as well as its effect on cell viability after light exposure through MTT assay and confocal imaging. Key findings: Bovine serum albumin binds curcumin with moderate affinity and solubilizes the hydrophobic compound preserving its photophysical properties for several hours. Cell viability assays demonstrate that when bound to serum albumin, curcumin is an effective photosensitizer for HeLa cells, with better performance than curcumin alone. Confocal fluorescence imaging reveals that when curcumin is delivered alone, it preferentially associates with mitochondria, whereas curcumin bound to bovine serum albumin is found in additional locations within the cell, a fact that may be related to the higher phototoxicity observed in this case. Significance: The higher bioavailability of the photosensitizing compound curcumin when bound to serum albumin may be exploited to increase the efficiency of the drug in photodynamic therapy of tumors.
JTD Keywords: Cancer, Curcumin, Live cell imaging, Photodynamic therapy
Pellequer, J. L., Parot, P., Navajas, D., Kumar, S., Svetli, Scheuring, S., Hu, J., Li, B., Engler, A., Sousa, S., Lekka, M., Szymo, Schillers, H., Odorico, M., Lafont, F., Janel, S., Rico, F., (2019). Fifteen years of Servitude et Grandeur to the application of a biophysical technique in medicine: The tale of AFMBioMed Journal of Molecular Recognition 32, (3), e2773
AFMBioMed is the founding name under which international conferences and summer schools are organized around the application of atomic force microscopy in life sciences and nanomedicine. From its inception at the Atomic Energy Commission in Marcoule near 2004 to its creation in 2007 and to its 10th anniversary conference in Krakow, a brief narrative history of its birth and rise will demonstrate how and what such an organization brings to laboratories and the AFM community. With the current planning of the next AFMBioMed conference in Münster in 2019, it will be 15 years of commitment to these events.
JTD Keywords: Atomic Force Microscopy, Single molecules, Biomechanics, Force spectroscopy, High-speed AFM, Imaging, Nanoindentation, Nanomedicine, Nanotoxicology
Feiner-Gracia, Natalia, Beck, Michaela, Pujals, Sílvia, Tosi, Sébastien, Mandal, Tamoghna, Buske, Christian, Linden, Mika, Albertazzi, Lorenzo, (2017). Super-resolution microscopy unveils dynamic heterogeneities in nanoparticle protein corona Small 13, (41), 1701631
The adsorption of serum proteins, leading to the formation of a biomolecular corona, is a key determinant of the biological identity of nanoparticles in vivo. Therefore, gaining knowledge on the formation, composition, and temporal evolution of the corona is of utmost importance for the development of nanoparticle-based therapies. Here, it is shown that the use of super-resolution optical microscopy enables the imaging of the protein corona on mesoporous silica nanoparticles with single protein sensitivity. Particle-by-particle quantification reveals a significant heterogeneity in protein absorption under native conditions. Moreover, the diversity of the corona evolves over time depending on the surface chemistry and degradability of the particles. This paper investigates the consequences of protein adsorption for specific cell targeting by antibody-functionalized nanoparticles providing a detailed understanding of corona-activity relations. The methodology is widely applicable to a variety of nanostructures and complements the existing ensemble approaches for protein corona study.
JTD Keywords: Heterogeneity, Mesoporous silica nanoparticles, Protein corona, Super-resolution imaging, Targeting
Climent, A. M., Hernandez-Romero, I., Guillem, M. S., Montserrat, N., Fernandez, M. E., Atienza, F., Fernandez-Aviles, F., (2017). High resolution microscopic optical mapping of anatomical and functional reentries in human cardiac cell cultures IEEE Conference Publications Computing in Cardiology Conference (CinC), 2016 , IEEE (Vancouver, Canada) 43, 233-236
Anatomical and/or functional reentries have been proposed as one of the main mechanism of perpetuation of cardiac fibrillation processes. However, technical limitations have difficult the characterization of those reentries and are hampering the development of effective anti-arrhythmic treatments. The goal of this study is to present a novel technology to map with high resolution the center of fibrillation drivers in order to characterize the mechanisms of reentry. Cell cultures of human cardiac-like cells differentiated from pluripotent stem cells were analyzed with a novel microscopic optical mapping system. The pharmacological response to verapamil administration of each type of reentry was analyzed. In all analyzed cell cultures, a reentry was identified as the mechanism of maintenance of the arrhythmia. Interestingly, the administration of verapamil produced opposite effects on activation rate depending on the mechanisms of reentry (i.e. anatomical or functional). Microscopic optical mapping of reentries allows the identification of perpetuation mechanisms which has been demonstrated to be linked with different pharmacological response.
JTD Keywords: Stem cells, Rotors, Microscopy, Optical filters, Calcium, Optical microscopy, Biomedical optical imaging
Bosch, M., Castro, J., Sur, M., Hayashi, Y., (2017). Photomarking relocalization technique for correlated two-photon and electron microcopy imaging of single stimulated synapses Synapse Development - Methods and Protocols (Methods in Molecular Biology) (ed. Poulopoulos , A.), Humana Press (New York, USA) 1538, 185-214
Synapses learn and remember by persistent modifications of their internal structures and composition but, due to their small size, it is difficult to observe these changes at the ultrastructural level in real time. Two-photon fluorescence microscopy (2PM) allows time-course live imaging of individual synapses but lacks ultrastructural resolution. Electron microscopy (EM) allows the ultrastructural imaging of subcellular components but cannot detect fluorescence and lacks temporal resolution. Here, we describe a combination of procedures designed to achieve the correlated imaging of the same individual synapse under both 2PM and EM. This technique permits the selective stimulation and live imaging of a single dendritic spine and the subsequent localization of the same spine in EM ultrathin serial sections. Landmarks created through a photomarking method based on the 2-photon-induced precipitation of an electrodense compound are used to unequivocally localize the stimulated synapse. This technique was developed to image, for the first time, the ultrastructure of the postsynaptic density in which long-term potentiation was selectively induced just seconds or minutes before, but it can be applied for the study of any biological process that requires the precise relocalization of micron-wide structures for their correlated imaging with 2PM and EM.
JTD Keywords: Correlated imaging, DAB, Dendritic spine, Photobranding, Photoetching, Photomarking, Postsynaptic density, Serial-section transmission electron microscopy, Synapse, Time-lapse live two-photon fluorescence microscopy
Van Der Hofstadt, M., Hüttener, M., Juárez, A., Gomila, G., (2015). Nanoscale imaging of the growth and division of bacterial cells on planar substrates with the atomic force microscope Ultramicroscopy , 154, 29-36
Abstract With the use of the atomic force microscope (AFM), the Nanomicrobiology field has advanced drastically. Due to the complexity of imaging living bacterial processes in their natural growing environments, improvements have come to a standstill. Here we show the in situ nanoscale imaging of the growth and division of single bacterial cells on planar substrates with the atomic force microscope. To achieve this, we minimized the lateral shear forces responsible for the detachment of weakly adsorbed bacteria on planar substrates with the use of the so called dynamic jumping mode with very soft cantilever probes. With this approach, gentle imaging conditions can be maintained for long periods of time, enabling the continuous imaging of the bacterial cell growth and division, even on planar substrates. Present results offer the possibility to observe living processes of untrapped bacteria weakly attached to planar substrates.
JTD Keywords: Atomic Force Microscope (AFM), Living cell imaging, Bacteria division, Gelatine immobilization, Dynamic jumping mode
Seo, K. D., Kwak, B. K., Sánchez, S., Kim, D. S., (2015). Microfluidic-assisted fabrication of flexible and location traceable organo-motor IEEE Transactions on Nanobioscience , 14, (3), 298-304
In this paper, we fabricate a flexible and location traceable micromotor, called organo-motor, assisted by microfluidic devices and with high throughput. The organo-motors are composed of organic hydrogel material, poly (ethylene glycol) diacrylate (PEGDA), which can provide the flexibility of their structure. For spatial and temporal traceability of the organo-motors under magnetic resonance imaging (MRI), superparamagnetic iron oxide nanoparticles (SPION; Fe3O4) were incorporated into the PEGDA microhydrogels. Furthermore, a thin layer of platinum (Pt) was deposited onto one side of the SPION-PEGDA microhydrogels providing geometrical asymmetry and catalytic propulsion in aqueous fluids containing hydrogen peroxide solution, H2O2. Furthermore, the motion of the organo-motor was controlled by a small external magnet enabled by the presence of SPION in the motor architecture.
JTD Keywords: Flexible, Hydrogel, Magnetic resonance imaging, Microfluidics, Micromotor, Microparticle, Organo-motor, Poly (ethylene glycol) diacrylate, Self-propulsion, Superparamagnetic iron oxide nanoparticles
Eckelt, Kay, Masanas, Helena, Llobet, Artur, Gorostiza, P., (2014). Automated high-throughput measurement of body movements and cardiac activity of Xenopus tropicalis tadpoles Journal of Biological Methods , 1, (2), e9
Xenopus tadpoles are an emerging model for developmental, genetic and behavioral studies. A small size, optical accessibility of most of their organs, together with a close genetic and structural relationship to humans make them a convenient experimental model. However, there is only a limited toolset available to measure behavior and organ function of these animals at medium or high-throughput. Herein, we describe an imaging-based platform to quantify body and autonomic movements of Xenopus tropicalis tadpoles of advanced developmental stages. Animals alternate periods of quiescence and locomotor movements and display buccal pumping for oxygen uptake from water and rhythmic cardiac movements. We imaged up to 24 animals in parallel and automatically tracked and quantified their movements by using image analysis software. Animal trajectories, moved distances, activity time, buccal pumping rates and heart beat rates were calculated and used to characterize the effects of test compounds. We evaluated the effects of propranolol and atropine, observing a dose-dependent bradycardia and tachycardia, respectively. This imaging and analysis platform is a simple, cost-effective high-throughput in vivo assay system for genetic, toxicological or pharmacological characterizations.
JTD Keywords: Xenopus tropicalis, Animal behavior, Cardiac imaging, Motion analysis, Animal tracking, Hhigh-throughput in vivo assay
Vila, O. F., Martino, M. M., Nebuloni, L., Kuhn, G., Pérez-Amodio, S., Müller, R., Hubbell, J. A., Rubio, N., Blanco, J., (2014). Bioluminescent and micro-computed tomography imaging of bone repair induced by fibrin-binding growth factors Acta Biomaterialia 10, (10), 4377-4389
In this work we have evaluated the capacity of bone morphogenetic protein-2 (BMP-2) and fibrin-binding platelet-derived growth factor-BB (PDGF-BB) to support cell growth and induce bone regeneration using two different imaging technologies to improve the understanding of structural and organizational processes participating in tissue repair. Human mesenchymal stem cells from adipose tissue (hAMSCs) expressing two luciferase genes, one under the control of the cytomegalovirus (CMV) promoter and the other under the control of a tissue-specific promoter (osteocalcin or platelet endothelial cell adhesion molecule), were seeded in fibrin matrices containing BMP-2 and fibrin-binding PDGF-BB, and further implanted intramuscularly or in a mouse calvarial defect. Then, cell growth and bone regeneration were monitored by bioluminescence imaging (BLI) to analyze the evolution of target gene expression, indicative of cell differentiation towards the osteoblastic and endothelial lineages. Non-invasive imaging was supplemented with micro-computed tomography (Î¼CT) to evaluate bone regeneration and high-resolution Î¼CT of vascular casts. Results from BLI showed hAMSC growth during the first week in all cases, followed by a rapid decrease in cell number; as well as an increment of osteocalcin but not PECAM-1 expression 3 weeks after implantation. Results from Î¼CT show that the delivery of BMP-2 and PDGF-BB by fibrin induced the formation of more bone and improves vascularization, resulting in more abundant and thicker vessels, in comparison with controls. Although the inclusion of hAMSCs in the fibrin matrices made no significant difference in any of these parameters, there was a significant increment in the connectivity of the vascular network in defects treated with hAMSCs.
JTD Keywords: Angiogenesis, Bioluminescence imaging, Bone regeneration, Fibrin, Mesenchymal stem cell
Lambrecht, Stefan, Urra, Oiane, Grosu, Svetlana, Pérez, Soraya, (2014). Emerging rehabilitation in cerebral palsy Biosystems & Biorobotics Emerging Therapies in Neurorehabilitation (ed. Pons, José L., Torricelli, Diego), Springer Berlin Heidelberg (London, UK) 4, 23-49
Cerebral Palsy (CP) is the most frequent disability affecting children. Although the effects of CP are diverse this chapter focuses on the impaired motor control of children suffering from spastic diplegia, particularly in the lower limb. The chapter collects the most relevant techniques that are used or might be useful to overcome the current limitations existing in the diagnosis and rehabilitation of CP. Special emphasis is placed on the role that emerging technologies can play in this field. Knowing in advance the type and site of brain injury could assist the clinician in selecting the appropriate therapy. In this context, neuroimaging techniques are being recommended as an evaluation tool in children with CP; we describe a variety of imaging technologies such as Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging (DTI), etc. But creating new knowledge in itself is not enough; there must be a transfer from progress through research to advances in the clinical field. The classic therapeutic approach of CP thus hampers the optimal rehabilitation of the targeted component. Traditional therapies may be optimized if complemented with treatments. We try to collect a wide range of emerging technologies and provide some criteria to select the adequate technology based on the characteristics of the neurological injury. For example, exoskeleton based over-ground gait training is suggested to be more effective than treadmill-based gait training. So, we suggest a new point of view combining different technologies in order to provide the foundations of a rational design of the individual rehabilitation strategy.
JTD Keywords: Cerebral palsy, Robotics, Neurostimulation, Neuroimaging, Myoelectric signals
Gorostiza, Pau, Arosio, Daniele, Bregestovski, Piotr, (2013). Molecular probes and switches for functional analysis of receptors, ion channels and synaptic networks Frontiers in Molecular Neuroscience 6, (Article 48), 1-2
Vila, Olaia F., Bagó, Juli R., Navarro, Melba, Alieva, Maria, Aguilar, Elisabeth, Engel, Elisabeth, Planell, Josep, Rubio, Nuria, Blanco, Jerónimo, (2013). Calcium phosphate glass improves angiogenesis capacity of poly(lactic acid) scaffolds and stimulates differentiation of adipose tissue-derived mesenchymal stromal cells to the endothelial lineage Journal of Biomedical Materials Research - Part A , 101A, (4), 932-941
The angiogenic capacity of a new biomaterial composite of poly(lactic acid) and calcium phosphate glass (PLA/CaP) was analyzed by noninvasive bioluminescence imaging (BLI) and histological procedures. Human adipose tissue-derived mesenchymal stromal cells expressing cytomegalovirus (CMV) promoter regulated Photinus pyralis luciferase (hAMSC-PLuc) grew up to 30 times the initial cell load, in vitro, when seeded in PLA/CaP scaffolds, but suffered an initial growth crisis followed by recovery when the scaffolds were subcutaneously implanted in SCID mice. To analyze changes in gene expression, hAMSC-PLuc cells were double labeled with a CMV promoter regulated Renilla reniformis luciferase and a Photinus pyralis luciferase reporter regulated by either the PECAM promoter or a hypoxia response element (HRE) artificial promoter and seeded in PLA/CaP and PLA scaffolds implanted in SCID mice. Analysis by BLI showed that hAMSCs in scaffolds were induced to differentiate to the endothelial lineage and did this faster in PLA/CaP than in PLA scaffolds. Endothelial differentiation correlated with a decrease in the activity of HRE regulated luciferase expression, indicative of a reduction of hypoxia. Histological analysis showed that PLA/CaP scaffolds were colonized by a functional host vascular system. Moreover, colonization by isolectin B4 positive host cells was more effective in PLA/CaP than in PLA scaffolds, corroborating BLI results.
JTD Keywords: Scaffold, Bioluminescence imaging, Cell differentiation, Angiogenesis, Mesenchymal stromal cells
Gil, V., Del Río, J. A., (2012). Analysis of axonal growth and cell migration in 3D hydrogel cultures of embryonic mouse CNS tissue Nature Protocols 7, (2), 268-280
This protocol uses rat tail-derived type I collagen hydrogels to analyze key processes in developmental neurobiology, such as chemorepulsion and chemoattraction. The method is based on culturing small pieces of brain tissue from embryonic or early perinatal mice inside a 3D hydrogel formed by rat tail-derived type I collagen or, alternatively, by commercial Matrigel. The neural tissue is placed in the hydrogel with other brain tissue pieces or cell aggregates genetically modified to secrete a particular molecule that can generate a gradient inside the hydrogel. The present method is uncomplicated and generally reproducible, and only a few specific details need to be considered during its preparation. Moreover, the degree and behavior of axonal growth or neural migration can be observed directly using phase-contrast, fluorescence microscopy or immunocytochemical methods. This protocol can be carried out in 4 weeks.
JTD Keywords: Cell biology, Cell culture, Developmental biology, Imaging, Model organisms, Neuroscience, Tissue culture
van Zanten, T. S., Garcia-Parajo, M. F., (2012). Super-resolution near-field optical microscopy Comprehensive Biophysics (ed. Egelman, E. H.), Elsevier (Desdren, Germany) Volume 2: Biophysical Techniques for Characterization of Cells, 144-164
Near-field optical microscopy is a technique not limited by the laws of diffraction that enables simultaneous high-resolution fluorescence and topographic measurements at the nanometer scale. This chapter highlights the intrinsic advantages of near-field optics in the study of cellular structures. The first part of the chapter lays the foundations of the near-field concept and technical implementation of near-field scanning optical microscopy (NSOM), whereas the second part of the chapter focuses on applications of NSOM to the study of model membranes and cellular structures on the plasma membrane. The last part of the chapter discusses further directions of near-field optics, including optical antennas and fluorescence correlation spectroscopy approaches in the near-field regime.
JTD Keywords: Biological membranes, Cell membrane nanoscale compartmentalization, Cellular nanodomains, Fluorescence correlation spectroscopy in reduced volumes, Immunoreceptor imaging, Lipid rafts, Near-field scanning optical microscopy, Optical nano-antennas, Shear force imaging, Single molecule detection, Super-resolution microscopy
Izquierdo-Useros, Nuria, Esteban, Olga, Rodriguez-Plata, Maria T., Erkizia, Itziar, Prado, Julia G., Blanco, Julia, Garcia-Parajo, Maria F., Martinez-Picado, Javier, (2011). Dynamic imaging of cell-free and cell-associated viral capture in mature dendritic cells Traffic , 12, (12), 1702-1713
Dendritic cells (DCs) capture human immunodeficiency virus (HIV) through a non-fusogenic mechanism that enables viral transmission to CD4(+) T cells, contributing to in vivo viral dissemination. Although previous studies have provided important clues to cell-free viral capture by mature DCs (mDCs), dynamic and kinetic insight on this process is still missing. Here, we used three-dimensional videomicroscopy and single-particle tracking approaches to dynamically dissect both cell-free and cell-associated viral capture by living mDCs. We show that cell-free virus capture by mDCs operates through three sequential phases: virus binding through specific determinants expressed in the viral particle, polarized or directional movements toward concrete regions of the cell membrane and virus accumulation in a sac-like structure where trapped viral particles display a hindered diffusive behavior. Moreover, real-time imaging of cell-associated viral transfer to mDCs showed a similar dynamics to that exhibited by cell-free virus endocytosis leading to viral accumulation in compartments. However, cell-associated HIV type 1 transfer to mDCs was the most effective pathway, boosted throughout enhanced cellular contacts with infected CD4(+) T cells. Our results suggest that in lymphoid tissues, mDC viral uptake could occur either by encountering cell-free or cell-associated virus produced by infected cells generating the perfect scenario to promote HIV pathogenesis and impact disease progression.
JTD Keywords: Dendritic cells, HIV-1, Live cell imaging, Trans-infection
Crespo, C., Gallego, J., Cot, A., Falcón, C., Bullich, S., Pareto, D., Aguiar, P., Sempau, J., Lomeña, F., Calviño, F., Pavía, J., Ros, D., (2008). Quantification of dopaminergic neurotransmission SPECT studies with 123I-labelled radioligands. A comparison between different imaging systems and data acquisition protocols using Monte Carlo simulation European Journal of Nuclear Medicine and Molecular Imaging , 35, (7), 1334-1342
Purpose: 123I-labelled radioligands are commonly used for single-photon emission computed tomography (SPECT) imaging of the dopaminergic system to study the dopamine transporter binding. The aim of this work was to compare the quantitative capabilities of two different SPECT systems through Monte Carlo (MC) simulation. Methods: The SimSET MC code was employed to generate simulated projections of a numerical phantom for two gamma cameras equipped with a parallel and a fan-beam collimator, respectively. A fully 3D iterative reconstruction algorithm was used to compensate for attenuation, the spatially variant point spread function (PSF) and scatter. A post-reconstruction partial volume effect (PVE) compensation was also developed. Results: For both systems, the correction for all degradations and PVE compensation resulted in recovery factors of the theoretical specific uptake ratio (SUR) close to 100%. For a SUR value of 4, the recovered SUR for the parallel imaging system was 33% for a reconstruction without corrections (OSEM), 45% for a reconstruction with attenuation correction (OSEM-A), 56% for a 3D reconstruction with attenuation and PSF corrections (OSEM-AP), 68% for OSEM-AP with scatter correction (OSEM-APS) and 97% for OSEM-APS plus PVE compensation (OSEM-APSV). For the fan-beam imaging system, the recovered SUR was 41% without corrections, 55% for OSEM-A, 65% for OSEM-AP, 75% for OSEM-APS and 102% for OSEM-APSV. Conclusion: Our findings indicate that the correction for degradations increases the quantification accuracy, with PVE compensation playing a major role in the SUR quantification. The proposed methodology allows us to reach similar SUR values for different SPECT systems, thereby allowing a reliable standardisation in multicentric studies.
JTD Keywords: Brain SPECT, Monte Carlo methods, Receptor imaging, Reconstruction quantification, SPECT instrumentation and algorithms
Manara, S., Paolucci, F., Palazzo, B., Marcaccio, M., Foresti, E., Tosi, G., Sabbatini, S., Sabatino, P., Altankov, G., Roveri, N., (2008). Electrochemically-assisted deposition of biomimetic hydroxyapatite-collagen coatings on titanium plate Inorganica Chimica Acta 361, (6), 1634-1645
A biomimetic bone-like composite, made of self-assembled collagen fibrils and carbonate hydroxyapatite nanocrystals, has been performed by an electrochemically-assisted deposition on titanium plate. The electrolytic processes have been carried out using a single type I collagen molecules suspension in a diluted Ca(NO3)(2) and NH4H2PO4 solution at room temperature and applying a constant current for different periods of time. Using the same electrochemical conditions, carbonate hydroxyapatite nanocrystals or reconstituted collagen. brils coatings were obtained. The reconstituted collagen. brils, hydroxyapatite nanocrystals and collagen fibrils/apatite nanocrystals coatings have been characterized chemically, structurally and morphologically, as well as for their ability to bind fibronectin (FN). Fourier Transform Infrared microscopy has been used to map the topographic distribution of the coating components at different times of electrochemical deposition, allowing to single out the individual deposition steps. Moreover, roughness of Ti plate has been found to affect appreciably the nucleation region of the inorganic nanocrystals. Laser scanning confocal microscopy has been used to characterize the FN adsorption pattern on a synthetic biomimetic apatitic phase, which exhibits a higher affinity when it is inter-grown with the collagen fibrils. The results offer auspicious applications in the preparation of medical devices such as biomimetic bone-like composite-coated metallic implants.
JTD Keywords: Hydroxyapatite-collagen coating, Electrochemically-assisted deposition, Micro-imaging FTIR spectroscopy, Laser scanning confocal microscopy, Biomimetic crystal growth, Fibronectin binding